1. Field of the Invention
The present invention relates generally to a method for forming a pattern and a semiconductor device, and in particular, to a method for forming a pattern for the formation of quantum dots or wires with 1xcx9c50 nm dimension using the atomic array of a crystalline material and to the manufacture of functional devices that have such a structure.
The present invention relates generally to a method for forming a pattern and a semiconductor device, and in particular, to a method for forming a pattern for the formation of quantum dots or wires having a nano or tens of nano meter order using the atomic array of a single or a poly crystalline material and to the manufacture of functional devices that have such a structure. The electron beam lithography method in accordance with the present invention uses the phase contrast atomic image of a single or a poly crystalline material itself.
2. Description of the Related Art
The formation process of quantum dots or wires becomes the core process for the fabrication of an electronic, magnetic, or optical device with quantum dots or wires as the application of such devices is increasingly expected. A fundamental operating principle of such devices is based on quantum mechanical results that the physical properties of the particle are greatly affected by its size as it becomes nanometer-sized. Particularly, there are many researches for the single electron transistor which has been suggested as the alternative to MOS device in order to overcome the limitation of the MOS device that has been developed continuously for 40 years.
Previous researches on the formation processes of quantum dots or wires can largely be divided as follows.
First, there is a method in which one or a few quantum dots or wires are formed by AFM (Atomic Force Microscopy), STM (Scanning Tunneling Microscopy) and electron beam lithography. This method has the capability to form the quantum dots or wires whose size and location are controlled experimentally, but has difficulty in applying to mass production because of a low throughput.
Second, there is a method in which quantum dots or wires are formed by the process of patterning and etching. In this method, patterning means the formation process of quantum dots or wires on the substrate by the electron beam direct-writing, or by the etching of the chemical substance which was imprinted by the mask or mold made with an electron beam.
Third, there is a method in which quantum dots or wires are formed by the nucleation at the early state of phase transition of materials. This method has can be applied to mass production, but has problems in controlling the size, density or distribution of quantum dots or wires.
Therefore, it is an object of the present invention to provide a method for forming a pattern using a crystal structure of a single or a poly crystalline material as a mask.
It is another object of the present invention to provide a method for forming quantum dots and wires of uniform size and density which can be controlled by patterning a layer using a crystal structure of a single or a poly crystalline material as a mask.
It is a further object of the present invention to provide a method for forming quantum dots and wires using a crystal structure of a single or a poly crystalline material for fabricating semiconductor devices in practice.
It is still another object of the present invention to provide a semiconductor device having the structure of quantum dots or wires. The foregoing and other objects of the present invention can be achieved by providing a method for forming a pattern wing a crystal structure of a single or poly crystalline material as a mask. According to one aspect of the present invention, a method for forming a pattern using a crystal structure of a single or poly crystalline material is comprising the steps of locating the material having a crystal structure in the chamber of the transmission electron microscope; radiating an electron beam to the material; forming a pattern from a lattice image of the material having a crystal structure on the surface of an irradiated material such as a electron beam resist deposited substrate by diffracted electron beam and transmitted electron beam passed through the material.
Preferably, the lattice image is formed by a method of the phase contrast imaging.
Preferably, the material having a crystal structure is processed into a thickness of a few tens of nanometer.
Preferably, the irradiated material is an electron beam resist deposited material on a semiconductor substrate.
Preferably, the semiconductor substrate has been applied with an electron beam resist deposited on after deposition of a gate oxide and an amorphous silicon on the substrate in which source and drain regions are already formed.